$$TI = \frac{\text{Toxic dose}}{\text{MIC}}$$

Question 1

Which of the following best describes the mechanism of action of beta-lactam antibiotics such as penicillin?

Accepted Answer

They inhibit the synthesis of peptidoglycan cross-links in bacterial cell walls.

Question 2

A patient with a fungal infection is prescribed amphotericin B. What is the primary target of this drug?

Accepted Answer

Ergosterol in the fungal cell membrane

Question 3

Which of the following is a reason why there are fewer drugs to treat eukaryotic infections compared to bacterial infections?

Accepted Answer

Eukaryotic cells share more similarities with human cells, making selective toxicity harder to achieve.

Question 4

Which of the following drugs is most likely to cause nephrotoxicity and is therefore used primarily as a topical antibiotic?

Accepted Answer

Polymyxin

Question 5

A physician prescribes a broad-spectrum antibiotic. What is a potential risk associated with this choice?

Accepted Answer

Development of a superinfection due to disruption of normal microbiota

Question 6

Which of the following best explains why beta-lactamase-producing bacteria are resistant to penicillins?

Accepted Answer

They produce an enzyme that destroys the beta-lactam ring of the antibiotic.

Question 7

Which of the following is the correct formula for the therapeutic index (TI) of an antimicrobial drug?

Accepted Answer

$$TI = \frac{	ext{Toxic dose}}{	ext{MIC}}$$

Question 8

Which of the following antimicrobial agents acts by inhibiting folic acid synthesis in bacteria?

Accepted Answer

Sulfonamides

Question 9

A patient is prescribed a combination of two antibiotics that enhance each other's effects. This interaction is known as:

Accepted Answer

Synergism

Question 10

Which of the following is a mechanism by which bacteria can acquire resistance to antimicrobial drugs?

Accepted Answer

Acquisition of R plasmids via horizontal gene transfer

Question 11

Which test is used to determine the minimum concentration of an antibiotic that inhibits visible growth of a microorganism?

Accepted Answer

Minimum inhibitory concentration (MIC) test

Question 12

Which of the following drugs is used to treat mycobacterial infections by disrupting mycolic acid synthesis?

Accepted Answer

Isoniazid

Question 13

Which of the following statements about the Kirby-Bauer disk diffusion test is TRUE?

Accepted Answer

A larger zone of inhibition around a disk indicates greater susceptibility of the bacterium to the antibiotic.

Question 14

Which of the following is a unique target for antifungal drugs that is not found in human cells?

Accepted Answer

Ergosterol synthesis

Question 15

A patient develops a severe allergic reaction after receiving penicillin. What is the most serious potential outcome?

Accepted Answer

Anaphylactic shock

Question 16

Which of the following best explains why tetracyclines should not be prescribed to pregnant women?

Accepted Answer

They can cross the placenta and deposit in fetal bones and teeth, causing discoloration and developmental issues.

Question 17

Which of the following is a correct statement about the use of antiviral drugs?

Accepted Answer

They often target unique aspects of viral metabolism, such as reverse transcriptase in HIV.

Question 18

Which of the following is a reason why maintaining a high concentration of an antimicrobial drug in a patient is important for preventing resistance?

Accepted Answer

It inhibits the pathogen long enough for the immune system to eliminate it.

Question 19

Which of the following is a characteristic of an ideal antimicrobial agent?

Accepted Answer

It is selectively toxic against a wide range of pathogens.

Question 20

Which of the following best describes the action of sulfonamides?

Accepted Answer

They act as competitive inhibitors of para-aminobenzoic acid (PABA) in folic acid synthesis.

Controlling Microbial Growth in the Body: Antimicrobial Drugs

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